Every episode of Fringe contains a hidden "next episode clue" that foreshadows something in the following episode. In the last Fringe episode "Welcome To Westfield", the Fringe team hides out with the survivors at Coolidge High School, where the mascot is "Killer Bees"...

In the Fringe episode "A Better Human Being", Walter believes the killers communicate like bees in a hive to protect themselves:

WALTER: However these bees are communicating, they are operating as one, doing whatever it takes to ensure the survival of the hive. If Sean and his half-brothers are linked in a telepathic network, then it is possible they have formed a collective identity.